Distance, Critical, of Alternative Path.
The length of air gap in an alternative path whose resistance joined to
the impedance of the rest of the conductors of the path just balances
the impedance of the other path.
Distance, Sparking.
The distance between electrodes, which a spark from a given Leyden jar
or other source will pass across.
Synonym--Explosive Distance.
Distillation.
The evaporation of a liquid by heat, and sometimes in a vacuum, followed
by condensation of the vapors, which distil or drop from the end of the
condenser. It is claimed that the process is accelerated by the liquid
being electrified.
Distributing Box.
In an electric conduit system, a small iron box provided for giving
access to the cable for the purpose of making house and minor
connections.
Synonym--Hand Hole.
Distributing Switches.
Switch systems for enabling different dynamos to supply different lines
of a system as required. Spring jacks, q. v., are used for the lines,
and plug switches for the dynamo leads. Thus, dynamos can be thrown in
or out as desired, without putting out the lights.
Distribution of Electric Energy, Systems of.
The systems of electric current distribution from central stations or
from private generating plants, mechanical or battery, the latter
primary or secondary. They include in general the alternating current
system and direct current systems. Again, these may be subdivided into
series and multiple arc, multiple-series and series-multiple
distribution, and the three, four, or five wire system may be applied to
multiple arc or multiple series systems. (See Alternating
Current--Current System--Multiple Arc--Multiple Series--Series
Multiple--Three Wire System.)
Door Opener, Electric.
An apparatus for opening a door by pushing back the latch. A spring then
draws the door open, and it is closed against the force of the spring by
the person entering. Electro-magnetic mechanism actuates the latch, and
is operated by a switch or press-button. Thus a person on the upper
floor can open the hall door without descending.
Dosage, Galvanic.
In electro-therapeutics the amount of electric current or discharge, and
duration of treatment given to patients.
Double Carbon Arc Lamp.
An arc lamp designed to burn all night, usually constructed with two
parallel sets of carbons, one set replacing the other automatically, the
current being switched from the burnt out pair to the other by the
action of the mechanism of the lamp.